"Never send a friend to buy your ammunition," muttered the hunter at the shooting bench beside me. He'd arrived at the range to sight in his rifle, and with a box of 7mm-08 ammunition in his hand and a 7mm Remington Magnum rifle on the bench, he went home without firing a shot. He reluctantly admitted it was his fault because he hadn't been specific enough when he told his buddy to pick up a box of "140-grain 7mm ammo."
Caliber confusion like that is getting easier all the time because more calibers show up on the shelf every year. As hunting and sport shooting grow in popularity, more new shooters join our ranks and need a little guidance as to what all that information printed on a box of ammunition means. Let's look at how to interpret the markings and data on a common box of ammunition.
CALIBER MARKINGS
Every box of ammo is clearly marked as to the caliber of the firearm for which it's intended. Caliber designations are the product of a standards organization known as SAAMI (Sporting Arms and Ammunition Manufacturers Institute). In collaboration with the developer, this organization establishes the dimensions and loading specifications of cartridges and assigns a name by which that caliber will be identified. All manufacturers then use that designation, which is essentially a proper name, to mark their firearms and ammunition. It's just like the name on your birth certificate, only not many people are named 6mm Creedmoor. So, the first lesson is to make sure the caliber marking on a firearm and the box of ammunition matches. Additionally, shooters should check each round of ammunition to make sure the headstamp marking is correct, and the ammunition looks like it's supposed to. It's not unheard of to find a stray round of the wrong ammunition in a box of factory cartridges. Mistakes happen; check everything.
The two fired cartridge cases seen here were found in the brass bucket at a local range. At left is a .300 Winchester Magnum mistakenly fired in a .300 Weatherby Magnum, and at right is a .303 Savage mistakenly fired in a .303 British. Be careful; cartridge designations matter!
PROJECTILE SPECIFICATIONS
Besides caliber, every box of ammunition contains markings as to the type of projectile loaded in the cartridges. Rifle ammunition normally does this by specifying the weight of the bullet in grains (7,000 grains in a pound), then adding specifics on the bullet, such as whether it's a hollow point, soft nose, or flat point. However, this varies by manufacturer and may include some rather cryptic abbreviations. Some common ones are SP – soft point, HP – hollow point, and BT – boat tail.
PRODUCT CODE
Besides caliber and projectile information, a product code is also marked on every box. This code is usually printed on the end flap, near the caliber marking, and takes different forms, depending on the manufacturer. Its purpose is to identify the particular loading of people and computers in the supply chain.
There's a lot of information on a box of ammo, including caliber designation, bullet weight, velocity, and trajectory. The five-digit number under the word "Hornady" is the product code, while the lot number appears below the muzzle velocity.
A retailer who wants more of this ammo on the shelf will make sure he specifies that product code number in his order. This number matters to a consumer because if a rifle shoots this ammo superbly, they'll want to buy the same product with the same load number again.
LOT NUMBER
Most boxes of ammunition are also marked with a lot number by the manufacturer. It's usually found in an obscure location, often inside a box's end flap, and consists of a series of letters and numbers, sometimes barely legible. Its primary purpose is to identify to the manufacturer the exact components, machine, date, and maybe even people used to load that box of ammunition. This is critical information for rifle shooters looking for maximum accuracy because factories regularly switch components (especially gunpowder) based on price and availability. This component change can dramatically affect how well a particular rifle shoots this ammo and point of impact.
Competitive shooters who use factory ammunition, especially rimfire shooters, test lot numbers extensively to identify one that shoots best in their rifles. Both military and law enforcement snipers do the same thing because lot numbers matter when looking for maximum accuracy. They then buy as much as can be found of that same lot number. It's the only way to assure absolute consistency in what's being fed to a rifle.
FACTORY RECOMMENDATIONS
A relatively new trend in ammo box marking is to place a recommendation on the box indicating what type of shooting activity the product is suitable for. These markings may be a short phrase or two but often take the form of various logos or silhouettes, including images of a paper or clay target or a representative animal. It's a great idea and has real potential for helping a neophyte find suitable ammunition. However, there is no standardized system yet, so the buyer needs to look carefully at the information provided.
Animal icons on a cartridge box indicate the species the ammo is recommended for.
VELOCITY AND TRAJECTORY
Another recent trend is to mark the projectile velocity a consumer can expect on the box. Then, this information is often paired with trajectory data. However, every shooter should be aware this is only approximate information and may have a limited relationship to reality. Only actual shooting and chronograph data will determine what trajectory ammunition produces in a rifle.
Reading a box of ammunition may not be as riveting as the latest Stephen Hunter novel, but it's worth the effort. Learning what it says on the box and how it applies to your needs means you'll become a better and safer shooter. And if you task a buddy with picking up some ammo for you, be precise.